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At least 19 recordsLinked to original sources
PubMed1977

The pigment architecture of the human occipital lobe.

With the aid of steromicroscopical examination of pigment preparations uo to 1,000 micronm thick the various areas of the occipital lobe of the human brain are described. In the occipital lobe there are three main cortical types, forming the striate, the parastriate area, and the peristriate zone. The parastriate area is a horseshoe-shaped fringe area adjacent to the primary visual field. It is conspicuously marked by a relatively dark stripe of pigmented granule cells dividing the fourth layer into a light upper, a pigmented middle, and a light lower zone, a unique feature of the parastriate area, which is not to be found in any other isocortical area. This three-fold layer disappears abruptly as one passes from the parastriate to a peristriate area, permitting the definitive determination of this boundary. The peristriate zone is quite large in the inferior and the lateral parts of the occipital lobe and comparatively small in the superior parts. Its peripheral boundaries do not coincide with the limits of the occipital lobe. Parts of the cuneus on the one side are covered by parietal and temporal areas, whereas peristriate areas on the other side penetrate widely into the temporal lobe along the medial occipitotemporal and to a lesser extent the parahippocampal gyrus. As regards pigment architecture, the peristriate zone is divisble into ten areas. A relatively simply organized area accompaines the parastriate area. The structure of the cortex changes gradually until one reaches the various fringe areas adjacent to the parietal and temporal areas. The limit adjoining the temporal areas is sharply traceable, since the lower of two light cortical stripes vanishes abruptly when passing from a peristriate to a temporal area. The most highly developed field, the area peristriata magnopyramidalis, occupies part of the inferolateral margin of the occipital lobe. It displays a wealth of large pyramids in the lower reaches of the third layer, which contain tightly packed and densely stained pigment granules forming large rounded aggregates in the basal cytoplasm. Pyramids of this type give the field a close resemblance to association fields such as the posterior speech area, where they are commonly encountered as the predominant neurons of the third layer.

Aged↗
PubMed1978

The evaluation of occipital lobe atrophy by computerized tomography before consideration of vertebral artery reconstructive surgery.

Occipital lobe atrophy can be identified on CT. In a review of 90 selected cases with brain ischemia symptoms, 45 cases were found to have hindbrain ischemia with symptoms of vertigo and/or 'blurred vision.' Ten cases (22%) had normal CT studies and 35 cases (78%) had abnormal CT studies. The CT brain scan of the cerebellum and occipital lobes has a place in determining whether a patient with clinical hindbrain ischemia is a candidate for angiography and vertebral artery bypass surgery.

Adolescent↗
PubMed1979

Transient bilateral occipital lobe ischemia: microembolization through a trigeminal artery.

Microembolization from an ulcerated carotid artery to both occipital lobes via a persistent trigeminal artery was observed in a patient presenting with episodic bilateral central scotomata. Symptomatic relief was obtained following carotid endarterectomy. This unique pathway which resulted in occipital lobe ischemia has not been previously reported.

Carotid Artery, Internal↗
PubMed1979

Laminar origins and terminations of cortical connections of the occipital lobe in the rhesus monkey.

Cortical connections within the occipital lobe (areas 17, 18 and 19) of the rhesus monkey are investigated with the autoradiographic and horseradish peroxidase procedures. Two efferent systems, each with a specific laminar organization, are observed. (1) Rostrally directed connections, from area 17 to 18, area 18 to 19 and area 19 to the inferotemporal region (area TE), originate from neurons in layer IIIc (and, in area 19, from a small complement of neurons in layer Va), and terminate in and around layer IV. (2) In contrast, connections in the reverse direction ('caudally directed' connections), from area TE to 19, area 19 to 18, and area 18 to 17, originate from neurons in layers Vb, VI and, to a lesser extent, IIIa, and terminate mainly in layer I. In addition, the laminar organization of several intrinsic and callosal connections are observed. In trinsic connections within areas 18 and 19 originate from neurons in layers IIIc and, to a lesser extent, Va, and terminate in vertical bands in layers I to IV. Callosal connections from areas 18, 19, and the caudal inferotemporal region originate from neurons mainly in layer IIIc. From areas 18 and 19, these callosal connections terminate in vertical bands in layers I through IV. Thus, different cortical projection systems are characterized by specific laminar distributions of efferent terminations as well as of their neurons of origin.

Animals↗
PubMed1975

Regional cerebral blood flow in delayed brain swelling following x-irradiation of the right occipital lobe in the monkey.

Four to 5 months after exposure of the right occipital lobe of the monkey to 3500 rads of X-irradiation there is a proliferative and degenerative lesion accompanied by a massive break in the blood-brain barrier. The resulting vasogenic edema causes gross swelling in the ipsilateral hemisphere, compression of the contralateral hemisphere with ventricular dilatation, and distortion of midline structures, which may result in herniation through the incisura and foramen magnum. The regional cerebral blood flow, determined by [14C]antipyrine method, at successive stages in the development and resolution of the delayed brain swelling shows a reduction of blood flow in white and gray matter, first regionally, then throughout the ipsilateral hemisphere and finally throughout the brain. This is accompanied by an increase in CSF pressure, CSF lactic dehydrogenase and total protein, and clinical signs of increased intracranial pressure. With resolution of CSF pressure, there is a return to baseline of CSF chemistry and partial resolution of the other parameters. The cerebral blood flow shows a greater recovery in gray than white matter, but there remains a diffuse depression suggesting a long-term impairment in cellular metabolism and/or blood flow regulatory mechanisms.

Animals↗
PubMed1978

Association and dissociation of visual functions in a case of bilateral occipital lobe infarction.

A severe restriction of the visual field was observed in a patient suffering a bilateral occipital lobe infarction. Soon after the lesion, the visual field had an angle of approx. 4 degrees. Some recovery was observed within the following months. Within the restricted visual field, several visual functions were tested. Increment threshold, for instance, was found to be one log unit higher than would normally be expected. Color vision was completely lost soon after the lesion, but some recovery was later observed. Although binocular interaction was demonstrated by the interocular transfer of after-effects, the patient never experienced steropsis. He also seemed unable to recognize faces. Dsepite the small visual field, optokinetic nystagmus could be elicited. A notable slowing down of visual analyses was observed in experiments on visual reaction time, on the inversion of the Necker cube, and on binocular rivalry. The complete loss of certain functions like steropsis or face recognition in contrast to a quantitative reduction of other functions like visual acuity or color perception can be discussed in the light of two conceptual models of perceptual processing. One model suggests the representation of different visual functions within one neuronal network, each function represented by a different number of neurons or a different algorithm within the network. The second model suggests a spatial segregation of different visual functions in different cortical areas that receive input from one common structure, presumably the striate cortex.

Aged↗
PubMed1977

Sensations of ocular movement in seizures originating in occipital lobe.

Two patients with structural lesions had illusions of eye movement as the earliest manifestation of their seizures. One patient had a right occipitoparietal arteriovenous malformation and the other had a tentorial meningioma encroaching on the left occipital lobe. Symptoms were controlled by anticonvulsants and subsequent surgery in both cases. The characteristic feature of this rare form of seizure onset is a unilateral sensation of eye movement in the absence of oscillopsia.

Adult↗
PubMed1979

Resolution of classic migraine after removal of an occipital lobe AVM.

A patient had a thirteen-year history of symptoms clinically indistinguishable from classic migraine: a slowly progressive visual fortification spectrum lasting 40 minutes, followed by a five- to six-hour throbbing unilateral headache with nausea and vomiting. After unsuccessful migraine therapy, investigation revealed a large occipital lobe arteriovenous malformation (AVM). Surgical removal of the AVM resulted in immediate and total resolution of all symptoms.

Adult↗
PubMed1977

A blood flow increase to a visual stimulus in the occipital lobe of the cat with brainstem transection at the pretrigeminal level.

The effects of visual stimulation on the cerebral blood flow were studied in pretrigeminal cats. The visual stimulus was a feather duster which was moved for 4-5 min in front of the cats eyes. The cerebral blood flow was measured each 15 min with [133]Xe clearance method in the left occipital lobe. The visual stimulation evoked an increase of the cerebral blood flow which was accompanied by an ocular following movements and a cortical EEG desynchronization. The arterial blood pressure was unchanged. All these responses habituated rapidly when the stimulus was repeated at 15 min intervals. A similar increase of the cerebral blood flow was obtained by 9 percent CO2 inhalation. The administration of amphetamine increased the cerebral blood flow, whereas Nembutal decreased it. The visual stimulus evokes an increase of the cerebral blood flow in a condition when the lower brainstem is separated from the cerebrum.

Amphetamine↗
PubMed1979

Alexia without agraphia: lateral and medial infarction of left occipital lobe.

Four cases of alexia without agraphia were studied by 99m-technetium pertechnetate brain scan. Two types of increased uptake were seen. One was of the triangular type near the midline in the posterior view, said to characterize an infarction in the distribution area of the posterior cerebral artery. This was associated with the well-known clinical picture of alexia without agraphia accompanied by hemianopia and color-naming defect, and was confirmed by postmortem examination. The other type of pathologic isotope uptake, observed in three patients, was more laterally placed, in the basal part of the left occipital lobe, and did not reach the midline. In these cases the alexia was transient and not associated with color-naming defects.

Adult↗
PubMed1975

The dorsomedial cortical visual area: a third tier area in the occipital lobe of the owl monkey (Aotus trivirgatus).

In the owl monkey, microelectrode mapping of Brodmann's area 19 indicates that this region contains part or all of at least 5 separate representations of the visual field, each of which adjoins the anterior border of V II and collectively are termed the third tier of cortical visual areas (V I is the first tier; V II is the second tier). Described in detail in this report is one of the third tier areas which is located on the dorsal surface and the adjacent medial wall of the occipital lobe and corresponds to a densely myelinated zone of cortex. In this dorsomedial area (DM), the representation of the horizontal meridian is partially split, and thus, like V II (see ref. 4) and the dorsolateral crescent5, DM is a second order transformation of the visual hemifield. In one abnormal owl monkey, a portion of the upper quadrant was represented twice in DM. This abnormal case may provide some clues as to how the normal pattern of visuotopic organization is established in the developing brain.

Animals↗
PubMed1978

Grating contrast detection perimetry in a patient with occipital lobe epilepsy.

A new perimetry technique is based upon detection of faint gratings. This method permits assessment of visual field abnormalities that are not detectable by Goldmann perimetry or tangent screen examination. These abnormalities occurred in a 57-year-old man with a seizure disorder of left occipital origin. The technique may have advantages over conventional field study methods for the early detection of geniculocalcarine pathology.

Adult↗
PubMed1979

Functional anatomy of occipital lobe seizures: an experimental study in rats.

Small amounts of penicillin were used to create a seizure focus in the primary visual cortex (area 17), extrastriate cortex (area 18 and 18a), and neighboring somatosensory and temporal areas in rats. Autoradiography with 14C-deoxyglucose was used to map the focus and the local cortical and long subcortical circuits. Mild seizures from area 17 were associated with focal spiking without behavioral manifestations. There was restricted utilization of local U-fiber circuits and ipsilateral subcortical visual system nuclei. Stronger seizures filled up the visual cortex and projected into adjacent neocortex and limbic cortex, the contralateral 17-18a border, and additional subcortical nuclei. Seizures originating in the posterior visual cortex were associated with prolonged afterdischarges and stereotyped behavioral manifestations, with spread into the posterior cingulum, the subicular complex, and the bilateral hippocampus. After analyzing the electrographic discharges, behavior, and seizure pathways in each animal, we conclude that ictal symptoms associated with seizures would not be the expression of the function of a cortical focus, but rather of the dysfunction of excessive discharges through many local and long circuits.

Animals↗